You've incorporated in Singapore. The paperwork is signed. Your bank account is open. And now you have roughly 30 days to set up tax infrastructure—GST registration, ACRA filing readiness, and bank feeds—before compliance gaps start costing you. The mistake most founders make is treating accounting software as something that can wait until month three or four. In Singapore, it cannot. GST is mandatory above SGD 1 million annual turnover (and you'll hit that faster than you think). ACRA requires annual accounts within six months of fiscal year-end. And the moment you miss a tax deadline or misfile an invoice, you're locked out of vendor relationships and exposed to audit flags. This is your actual day-one checklist—what needs to be in place before your first invoice goes out, and what happens if you skip it. GST registration: timing and CrimsonLogic setup Singapore's GST regime is managed through CrimsonLogic, the government's digital platform. You don't register with ACRA directly; you register via MyBusiness portal or directly through CrimsonLogic. And the clock starts the moment you exceed SGD 1 million in annual turnover. Here's the real risk: if you invoice clients before you're GST-registered and you later exceed the threshold, you'll owe back GST on all those invoices—and your clients won't reimburse you. That's a cash impact, not a timing issue. What you need to do: Register for GST as soon as incorporation is complete. Do not wait until you hit SGD 1 million. Pre-register now so that when you do reach the threshold, you're already in the system and compliant from day one of invoicing. Get your GST Unique Entity Number (UEN). Your accounting software needs this. Your invoices need this. Every tax return needs this. Understand your tax period. GST returns in Singapore are typically monthly or quarterly depending on your turnover profile. Confirm this in your registration documents. Set up a GST liability account in your accounting ledger now. Do not wait until month three. Every invoice you issue is a GST obligation, and your ledger needs to track it separately from your revenue. Once you have your UEN, your accounting software (Xero, Wave, or Orin's invoicing module ) needs to be configured to automatically calculate and itemize GST on every invoice. If this step is manual or ad-hoc, you will make errors at scale. Bank integration and the reconciliation reality ACRA requires audited or reviewed financial statements. That means your bank records must reconcile perfectly with your invoiced revenue and recorded expenses. If they don't, the audit flags it, and you're back-explaining discrepancies on ACRA's timeline, not yours. This sounds obvious, but most founders don't connect their bank account to their accounting software until month two or three. By then, 40–60 transactions are already recorded manually or partially, and the reconciliation becomes a forensic exercise. On day one: Enable bank feeds in your accounting software. Xero connects to DBS, UOB, OCBC, and Maybank directly. Orin integrates with your bank feeds via middleware. Set this up before you make a single transfer. Reconcile your opening balances. If you're starting with founder capital, make sure that transfer is recorded as equity, not revenue. This is a common error that distorts your P&L and confuses tax calculations. Tag every transaction in the first 30 days. Do not let bank transactions sit unreconciled. The habit you build in week one determines whether you're reconciling daily or quarterly—and quarterly reconciliation in Singapore is a compliance risk. ACRA filing deadlines and what your accountant needs to prepare Singapore's ACRA requires annual accounts to be filed within 30 days of approval by the board, but no later than four months and 30 days after the end of your financial year-end. For most SMBs, that's approximately six months from fiscal close. The problem: if your accounting records are a mess on month nine, you're compressing financial statement preparation, tax filing, and audit (if required) into a three-week window. Mistakes happen when you're rushed, and auditors charge premium rates for urgent engagements. Set up your chart of accounts on day one so it maps directly to ACRA's filing requirements. This means: Revenue categories that distinguish between taxable sales, exempt supplies (if applicable), and GST collected. Expense categories that align with ACRA's statutory disclosure requirements (travel, depreciation, staff costs separate from contractors, professional fees, etc.). Fixed assets tracked separately from consumables (ACRA requires depreciation schedules, and your software needs to generate these automatically). Related-party transactions clearly tagged. If you're borrowing from founders or transacting with related entities, ACRA requires disclosure, and your software needs to flag these. If your accounting software doesn't support multi-currency (if you invoice USD clients or have overseas suppliers)