Why accrue at all
Gratuity is earned as each year of service passes, so under accrual accounting the cost belongs in the years the employee works, not the month they leave. IAS 19 treats end-of-service benefits like this as post-employment benefits. Larger companies often obtain an actuarial valuation; many SMEs use a simpler approach that calculates the amount payable if every eligible employee left at the reporting date.
Our view: for a business with fewer than fifty staff, the simple method, updated monthly and reviewed by the auditor at year end, is proportionate. Confirm with your auditor which method they will accept.